Speaker
Description
We present a comprehensive timing analysis of 50 X-ray light curves of the blazar Mrk 421, obtained over 17 years with the {\it XMM-Newton} satellite. Using both deterministic and stochastic approaches, we investigate the multi-scale nature of its variability. Deterministic dynamics are examined through an adaptive implementation of Recurrence Quantification Analysis (RQA), where systematically varied thresholds reveal scale-dependent structures in the emission. In parallel, autoregressive moving average (ARMA) and autoregressive integrated moving average (ARIMA) models characterize stochastic behavior across temporal scales.
Our results indicate that Mrk 421’s X-ray emission arises from a complex interplay of deterministic and stochastic processes. Deterministic patterns are localized at smaller temporal scales, while stochastic fluctuations propagate across both scales. Noise contributes at all scales, as shown by correlation analysis. This framework not only clarifies the physical processes driving the blazar’s X-ray variability but also demonstrates the potential of adaptive RQA for studying multi-scale behavior in other astrophysical sources.